NASCAR was born, raised, and became huge in the south. NASCAR's birth was deep in the North Carolina mountains, when bootleggers were running moonshine down to the "metropolitan" cities. NASCAR's adolescense was spent on the beaches of Daytona, when a bunch of "good 'ol boys" would take their hotrods out on the beach.
If you are at all interested in NASCAR and intrigued about the history behind the phenomonon that it has become, I strongly suggest that you read "The Wildest Ride: A History of NASCAR (or How a Bunch of Good Ol' Boys Built a Billion-Dollar Industry out of Wrecking Cars)" by Joe Menzer.
I am a NASCAR fanatic - I was born and raised in the south, and have been called a "hillbilly" or a "redneck" more times that I can count - and I don't care. I am college educated, have all my teeth, and didn't marry anyone within my gene pool.
NASCAR and rednecks are associated because that is all that you see on TV - the cameras pick the loudest, drunkest, and most attention grabbing individuals to put on camera. Unfortunately, most of the time, it is the man wearing no shirt, face painted, missing a few teeth, and wearing a cardboard Budweiser case on his head. Just keep in mind that NASCAR is a multi-billion dollar industry and growing everyday - there are a whole lot of highly educated and intellegent individuals who count down the days to Daytona and live for Sunday afternoons.
Hope this helps and provides some insight.